Journal of Molecular Biomarkers & Diagnosis

Melanoma is the most aggressive skin cancer and, despite great progresses recently assessed into the biology research and the diagnosis approaches, its incidence and mortality have extremely risen in all developed countries during the last half century

Background: Selected aberrantly methylated genes represent sensitive candidate stool markers for colorectal cancer (CRC) screening. We assessed the impact of demographic, exposure, body mass, and other patient variables on stool levels of highly informative methylated gene markers — BMP3, NDRG4, vimentin, and TFPI2. Methods: We studied freezer-archived stools from 500 patients with normal colonoscopy (median age 64 (range 44-85); 53% women). On supernatants from thawed aliquots, target gene sequences were purified by hybrid capture; bisulfite treated, and assayed using the analytically-sensitive QuARTS method (quantitative allele-specific real-time target and signal amplification). The reference human gene β-actin was assayed along with the 4 methylated genes. Results: Only age significantly influenced all methylated marker levels in stool (p<0.0001 for each). The relative increase per standard deviation of age was greatest with TFPI2 at 49.4% and least with BMP3 at only 0.21%; levels of β-actin did not change across age. Other demographic variables (sex, race, and residence), exposures (smoking, alcohol, or analgesic use), family or personal history of colorectal neoplasia, body mass, and diabetes mellitus had no effect on methylated marker levels. Conclusions: Although stool levels of candidate methylated markers increase with age to variable extents, most common clinical covariates have no effect. Impact: These findings have important implications on CRC screening compliance, as patients using a stool test that incorporates these markers would not have to make life-style or medication adjustments. Furthermore, age effect can be mitigated by adjustment of cut-off levels based on age or by selection of markers least influenced by age.